[1] Azienda Osped Univ Integrata, Cyst Fibrosis Ctr, I-37126 Verona, Italy
[2] Leeds Teaching Hosp Trust, Paediat CF Unit, Leeds, W Yorkshire, England
[3] Leeds Teaching Hosp Trust, Adult CF Unit, Leeds, W Yorkshire, England
[4] Univ Nottingham, Sch Med, Div Child Hlth Obstet & Gynaecol COG, Nottingham NG7 2RD, England
[5] Univ Childrens Hosp, CF Unit, Tubingen, Germany
[6] Queens Univ Belfast, Sch Med Dent & Biomed Sci, Belfast BT7 1NN, Antrim, North Ireland